157 research outputs found
Duality in interacting particle systems and boson representation
In the context of Markov processes, we show a new scheme to derive dual
processes and a duality function based on a boson representation. This scheme
is applicable to a case in which a generator is expressed by boson creation and
annihilation operators. For some stochastic processes, duality relations have
been known, which connect continuous time Markov processes with discrete state
space and those with continuous state space. We clarify that using a generating
function approach and the Doi-Peliti method, a birth-death process (or discrete
random walk model) is naturally connected to a differential equation with
continuous variables, which would be interpreted as a dual Markov process. The
key point in the derivation is to use bosonic coherent states as a bra state,
instead of a conventional projection state. As examples, we apply the scheme to
a simple birth-coagulation process and a Brownian momentum process. The
generator of the Brownian momentum process is written by elements of the
SU(1,1) algebra, and using a boson realization of SU(1,1) we show that the same
scheme is available.Comment: 13 page
Methodological considerations in the analysis of fecal glucocorticoid metabolites in tufted capuchins (Cebus apella)
Analysis of fecal glucocorticoid (GC) metabolites has recently become the standard method to monitor adrenocortical activity in primates noninvasively. However, given variation in the production, metabolism, and excretion of GCs across species and even between sexes, there are no standard methods that are universally applicable. In particular, it is important to validate assays intended to measure GC production, test extraction and storage procedures, and consider the time course of GC metabolite excretion relative to the production and circulation of the native hormones. This study examines these four methodological aspects of fecal GC metabolite analysis in tufted capuchins (Cebus apella). Specifically, we conducted an adrenocorticotrophic hormone (ACTH) challenge on one male and one female capuchin to test the validity of four GC enzyme immunoassays (EIAs) and document the time course characterizing GC me- tabolite excretion in this species. In addition, we compare a common field-friendly technique for extracting fecal GC metabolites to an established laboratory extraction methodology and test for effects of storing “field extracts” for up to 1 yr. Results suggest that a corticosterone EIA is most sensitive to changes in GC production, provides reliable measures when extracted according to the field method, and measures GC metabolites which remain highly stable after even 12 mo of storage. Further, the time course of GC metabolite excretion is shorter than that described yet for any primate taxa. These results provide guidelines for studies of GCs in tufted capuchins, and underscore the importance of validating methods for fecal hormone analysis for each species of interest
Stem cell factor and its soluble receptor (c-kit) in serum of asthmatic patients- correlation with disease severity
<p>Abstract</p> <p>Background</p> <p>SCF (stem cell factor) is a pleiotropic cytokine exerting its role at different stages of bone marrow development and affecting eosinophil activation, mast cells and basophil chemotaxis and survival. The aim of the study was to assess concentration of SCF and its soluble receptor c-kit (sc-kit) in peripheral blood of patients with asthma referring it to asthma severity and phenotype.</p> <p>Methods</p> <p>The study involved 107 patients with bronchial asthma, well characterized with respect to severity and 21 healthy controls. Concentration of SCF and sc-kit in the patients serum were measured by ELISA method.</p> <p>Results</p> <p>Mean serum SCF level in the group of asthmatics (n = 88) was significantly higher as compared to healthy controls (1010 pg/ml ± 37 vs 799 ± 33; p < 0,001). The level of SCF was higher in patients with severe asthma as compared to patients with non-severe asthma (1054 +/- 41 pg/ml vs 819 +/- 50; p < 0,01) and correlated with dose of inhaled glucocorticosteroids taken by the patients to achieve asthma control (R = 0,28; p < 0,01). The mean sc-kit serum level did not differ between asthmatic patients and healthy controls, however the level of sc-kit in non-severe asthmatics was significantly higher as compared to patients with severe asthma and healthy controls. In asthmatic patients (n = 63) the level of sc-kit correlated positively with FEV1% predicted value (R = 0,45; p < 0,001) and MEF25% predicted value (R = 0,33; p < 0,01). The level of sc-kit inversely correlated with the dose of inhaled glucocorticosteroids taken by the patients (R = -0,26; p < 0,01).</p> <p>Conclusion</p> <p>Serum levels of SCF and its soluble receptor c-kit seem to be reflect asthma severity suggesting a role for these molecules in asthmatic inflammation.</p
Stochastic Duality and Orthogonal Polynomials
For a series of Markov processes we prove stochastic duality relations with duality functions given by orthogonal polynomials. This means that expectations with respect to the original process (which evolves the variable of the orthogonal polynomial) can be studied via expectations with respect to the dual process (which evolves the index of the polynomial). The set of processes include interacting particle systems, such as the exclusion process, the inclusion process and independent random walkers, as well as interacting diffusions and redistribution models of Kipnis–Marchioro–Presutti type. Duality functions are given in terms of classical orthogonal polynomials, both of discrete and continuous variable, and the measure in the orthogonality relation coincides with the process stationary measure
Estrogen and Progestogen Correlates of the Structure of Female Copulation Calls in Semi-Free-Ranging Barbary Macaques (Macaca sylvanus)
Females of many Old World primates produce conspicuous vocalizations in combination with copulations. Indirect evidence exists that in Barbary macaques (Macaca sylvanus), the structure of these copulation calls is related to changes in reproductive hormone levels. However, the structure of these calls does not vary significantly around the timing of ovulation when estrogen and progestogen levels show marked changes. We here aimed to clarify this paradox by investigating how the steroid hormones estrogen and progesterone are related to changes in the acoustic structure of copulation calls. We collected data on semi-free-ranging Barbary macaques in Gibraltar and at La Forêt des Singes in Rocamadour, France. We determined estrogen and progestogen concentrations from fecal samples and combined them with a fine-grained structural analysis of female copulation calls (N = 775 calls of 11 females). Our analysis indicates a time lag of 3 d between changes in fecal hormone levels, adjusted for the excretion lag time, and in the acoustic structure of copulation calls. Specifically, we found that estrogen increased the duration and frequency of the calls, whereas progestogen had an antagonistic effect. Importantly, however, variation in acoustic variables did not track short-term changes such as the peak in estrogen occurring around the timing of ovulation. Taken together, our results help to explain why female Barbary macaque copulation calls are related to changes in hormone levels but fail to indicate the fertile phase
Characterization and social correlates of fecal testosterone and cortisol excretion in wild male Saguinus mystax
Reproductive success in male primates can be influenced by testosterone (T) and cortisol (C). We examined them in wild Saguinus mystax via fecal hormone analysis. Firstly, we wanted to characterize male hormonal status over the course of the year. Further we tested the influence of the reproductive status of the breeding female, social instability, and intergroup encounter rates on T levels, comparing the results with predictions of the challenge hypothesis (Wingfield et al., 1990). We also tested for interindividual differences in hormonal levels, possibly related to social or breeding status. We collected data during a 12-mo study on 2 groups of moustached tamarins at the Estación Biológica Quebrada Blanco in northeastern Peru. We found fairly similar T and C levels over the course of the year for all males. Yet an elevation of T shortly after the birth of infants, during the phase of ovarian inactivity of the group’s breeding female, was evident. Hormonal levels were not significantly elevated during a phase of social instability, did not correlate with intergroup encounter rates, and did not differ between breeding and nonbreeding males. Our results confirm the challenge hypothesis (Wingfield et al., 1990). The data suggest that reproductive competition inmoustached tamarins is not based on endocrinological, but instead on behavioral mechanisms, possibly combined with sperm competition.Deutsche Forschungsgemeinschaft (HE 1870/10-1,2
Platelet number and interleukin-6 correlate with VEGF but not with bFGF serum levels of advanced cancer patients
Nucleotide-Oligomerization-Domain-2 Affects Commensal Gut Microbiota Composition and Intracerebral Immunopathology in Acute Toxoplasma gondii Induced Murine Ileitis
Background Within one week following peroral high dose infection with
Toxoplasma (T.) gondii, susceptible mice develop non-selflimiting acute
ileitis due to an underlying Th1-type immunopathology. The role of the innate
immune receptor nucleotide-oligomerization-domain-2 (NOD2) in mediating
potential extra-intestinal inflammatory sequelae including the brain, however,
has not been investigated so far. Methodology/Principal Findings Following
peroral infection with 100 cysts of T. gondii strain ME49, NOD2-/- mice
displayed more severe ileitis and higher small intestinal parasitic loads as
compared to wildtype (WT) mice. However, systemic (i.e. splenic) levels of
pro-inflammatory cytokines such as TNF-α and IFN-γ were lower in NOD2-/- mice
versus WT controls at day 7 p.i. Given that the immunopathological outcome
might be influenced by the intestinal microbiota composition, which is shaped
by NOD2, we performed a quantitative survey of main intestinal bacterial
groups by 16S rRNA analysis. Interestingly, Bifidobacteria were virtually
absent in NOD2-/- but not WT mice, whereas differences in remaining bacterial
species were rather subtle. Interestingly, more distinct intestinal
inflammation was accompanied by higher bacterial translocation rates to extra-
intestinal tissue sites such as liver, spleen, and kidneys in T. gondii
infected NOD2-/- mice. Strikingly, intracerebral inflammatory foci could be
observed as early as seven days following T. gondii infection irrespective of
the genotype of animals, whereas NOD2-/- mice exhibited higher intracerebral
parasitic loads, higher F4/80 positive macrophage and microglia numbers as
well as higher IFN-γ mRNA expression levels as compared to WT control animals.
Conclusion/Significance NOD2 signaling is involved in protection of mice from
T. gondii induced acute ileitis. The parasite-induced Th1-type immunopathology
at intestinal as well as extra-intestinal sites including the brain is
modulated in a NOD2-dependent manner
Effects of GnRH vaccination in wild and captive African Elephant bulls (Loxodonta africana) on reproductive organs and semen quality
OBJECTIVES:
Although the African elephant (Loxodonta africana) is classified as endangered by the International
Union for Conservation of Nature (IUCN), in some isolated habitats in southern Africa,
contraception is of major interest due to local overpopulation. GnRH vaccination has been
promoted as a non-invasive contraceptive measure for population management of overabundant
wildlife. We tested the efficacy of this treatment for fertility control in elephant bulls.
METHODS:
In total, 17 male African elephants that were treated with a GnRH vaccine were examined in
two groups. In the prospective study group 1 (n = 11 bulls, ages: 8±36 years), semen quality,
the testes, seminal vesicles, ampullae and prostate, which were all measured by means of
transrectal ultrasound, and faecal androgen metabolite concentrations were monitored over
a three-year period. Each bull in the prospective study received 5 ml of Improvac® (1000 μg
GnRH conjugate) intramuscularly after the first examination, followed by a booster six
weeks later and thereafter every 5±7 months. In a retrospective study group (group 2, n = 6,
ages: 19±33 years), one examination was performed on bulls which had been treated with
GnRH vaccine for 5±11 years.
RESULTS:
In all bulls of group 1, testicular and accessory sex gland sizes decreased significantly after
the third vaccination. In six males examined prior to vaccination and again after more than
five vaccinations, the testis size was reduced by 57.5%. Mean testicular height and length
decreased from 13.3 ± 2.6 cm x 15.2 ± 2.8 cm at the beginning to 7.6 ± 2.1 cm x 10.2 ± 1.8
cm at the end of the study. Post pubertal bulls (>9 years, n = 6) examined prior to vaccination
produced ejaculates with viable spermatozoa (volume: 8±175 ml, sperm concentration:
410-4000x106/ml, total motility: 0±90%), while after 5±8 injections, only 50% of these bulls
produced ejaculates with a small number of immotile spermatozoa. The ejaculates of group
2 bulls (vaccinated >8 times) were devoid of spermatozoa. Faecal androgen metabolite concentrations
measured in captive males decreased significantly after the fourth vaccination.
None of the males entered musth during the treatment period.
CONCLUSIONS:
Our results showed a marked decrease in semen quality, testicle and secondary sex gland
sizes following repeated GnRH vaccinations. After 2±4 years of continuous treatment every
5±7 months, the effects were similar to surgical castration.ISIScopu
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